The present invention relates to a controller and a switch, and more particularly, to a controller and a switch for use in a smart key system of a vehicle.
A smart key system provided with a smart entry function and/or a smart ignition function as described in Japanese Laid-Open Patent Publication No. 2002-029385 has been proposed to improve security and convenience in an automobile. A portable device having the same ID code as that of an automobile is used for an automobile provided with a smart entry function and a smart ignition function. The portable device transmits a signal including the ID code to the automobile. In the automobile, a controller compares and verifies the ID code of the portable device with the ID code of the automobile. When the two ID codes match, the controller unlocks the door (smart entry) or enables the starting of the engine (smart ignition). More specifically, the smart entry function automatically unlocks the automobile door when the driver (user) who is carrying the portable device approaches the automobile. Further, the smart entry function automatically locks the door when the driver moves away from the automobile. The smart ignition function enables the controller of the automobile to start the engine when the driver enters the automobile while holding the portable device.
Accordingly, by using the smart functions (i.e., smart entry function and smart ignition function), the driver does not have to perform burdensome key operations when getting into or out of the vehicle and when starting the engine. This improves convenience. In addition, the door is not unlocked and the starting of the engine is not enabled unless the driver is carrying the portable device, which is extremely difficult to duplicate compared with a conventional mechanical key. This improves security.
The portable device, which realizes the smart function, uses a battery as a power source. When the battery is drained, communication cannot be performed between the portable device and the controller of the automobile. This invalidates the smart function. Thus, an immobilizer function is used in lieu of the smart ignition function when the battery of the portable device is drained. An immobilizer key having a key code that is the same as that of the automobile is used to realize the immobilizer function. An immobilizer key is a mechanical key including a transponder or a box-shaped portable device including a transponder. During usage of the immobilizer key, the controller of the automobile enables the starting of the engine when the key code of the immobilizer key matches the key code of the automobile and is thus verified.
More specifically, the transponder generates electromotive force when receiving electromagnetic waves of a predetermined intensity from the automobile. The electromotive force is used to transmit a signal including the key code to the automobile. In other words, the transponder functions without a power source.
When the battery of the portable device is drained, the immobilizer function is used in lieu of the smart function as described above. To use the immobilizer function, the driver inserts the immobilizer key in a key cylinder or a slot arranged in the automobile. When detecting the insertion of the immobilizer key, the controller of the automobile switches the smart function to the immobilizer function. In this structure, the arrangement of a key cylinder or a slot for receiving the immobilizer key increases cost and occupies space.
To solve this problem, the key cylinder or slot may be eliminated. However, the driver cannot use the immobilizer function without a trigger for switching the smart function to the immobilizer function. In other words, in the prior art, an automobile must have the key cylinder or slot to switch the communication control from normal control in which the smart function is valid to backup control in which the smart function is invalid.
Japanese Laid-Open Patent Publication No. 2001-311333 describes an engine control system provided with a smart ignition function. The engine control system includes a portable device rest and/or a portable device holder in the passenger compartment. The portable device rest or portable device holder includes a switch for detecting that the portable device is resting on the portable device rest or being held in the portable device holder. When the portable device is detected as being received by the rest or holder, communication control is switched from normal control in which the smart function is valid to backup control in which the smart function is invalid. This enables the driver to easily switch the communication control between normal control and backup control in accordance with the circumstances and increases the operability of the vehicle.
The communication area in which the portable device and the controller communicate with each other during backup control is normally much smaller than the communication area during normal control. Further, the switch may detect objects other than the portable device. Thus, in a state in which communication between the portable device and the controller is possible, when the communication control is switched from normal control to backup control even though the driver does not intend to do so, the driver may not be able to start the engine using the smart ignition function. That is, the arrangement of an object other than the portable device in the portable device rest or holder may switch the communication control from normal control to backup control even when the drive does not intend to do so. In such a case, the engine cannot be started since the necessary verification cannot be performed through communication between the portable device and the engine controller. This may mislead the driver into believing that the engine control system is not functioning properly.
The present invention provides a controller and a switch that enables the communication control to be switched from the smart function to the immobilizer function without using a key cylinder or a slot. Further, the present invention provides a controller that ensures the execution of ID verification through communication with a portable device.